ページネーションよりcursor型の実装

db_migrate.rb

# frozen_string_literal: true

class AlterContentIdColumns < ActiveRecord::Migration[5.1]
  def change
    [
      :contents,
      :products
    ].each do |table|
      add_column table, :uuid, :'CHAR(26)', unique: true, index: true, after: :id
    end
  end
end

Gemfile

# sortable uuid
gem 'ulid', require: false

paginatable.rb

# frozen_string_literal: true

require_dependency 'api/v1/application_controller'

module Api
  module V1
    module Timeline
      module Paginatable
        extend ActiveSupport::Concern
        # pagination
        # FIXME: 再利用性があるように書き換える。
        def cursor_paginate(klass, cursor: nil)
          last_page = klass.last&.uuid
          klass = klass.where("`uuid` < '#{cursor}'") if cursor.present?
          klass = klass.limit(20)
          @next_page = klass.last&.uuid
          response.headers['Link'] = last_page != @next_page && !@next_page.nil? ? "page=#{@next_page}" : ''
          klass
        end
      end
    end
  end
end